﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace A74
{
    class Program
    {
        static void Main(string[] args)
        {
            new B(2,3);
        }
    }
    class A
    {
        protected  int x;

        public A()//建议保留默认构造函数
        {

        }
        public A(int x)
        {
            this.x = x;
        }
    }
    class B : A
    {
        private int y;
        public B(int x,int y) : base(x)
        {
            this.y = y;
        }
    }
}
